Was I completely misinformed as a
child? I remember learning in grade
school that this phrase came from how easily these letters, in their lower
case form, could be confused on movable type printing presses.

From Lin Sims:

When I was growing up, this was an admonition to mind my manners, as in
"Mind your "pleases" (Ps) and "thank you's" (Qs). Probably the first place I heard it was in the English public school (equivalent to the
USA's private schools, and that's something I'd love to know how it happened!) I briefly attended when my dad was stationed in England.
No
cites or references, sorry. I wish I had them.

No need to panic! Check Issue
53 where
we discussed several of the suggested derivations for mind your p's and
q's.

From Anthony Stevens:

Malcolm Tent gripes about a migration of subject in the phrase "coal prices
are forecasting..." and clearly objects to being bludgeoned by such clumsy
reportage. I submit this is nothing more than a standard feature of English
language evolution in colloquial use.

Malcolm has doubtless 'flown into an airport' at some time - yet we all
understand he has neither grown wings nor smeared himself across a control
tower. Halibut may be 'landing at record values on the quayside' this week
- yet we do not expect fish to start making their own transport arrangements, let alone quoting the odds on the latest Madonna album.

As for casted, the suffix -ed makes for clarity of past tense through
analogy with hundreds of other established verbs. I have it ringed in my
Collected Shakespeare - if casted was good enough for William, it fits the
bill for me...

No, I can safely forecast: I would rather be bludgeoned than curmudgeoned to
death!

It may be evolution in
process but right now it's still considered incorrect to use forecasting
in the manner that Malcolm Tent discussed last
week. Until that usage becomes
widespread and, finally, accepted, Malcolm says, he'll continue to label
it incorrect. He doesn't think "flown into an airport" is
at all analogous to the problem discussed with "coal prices" and
"forecasting".

As for something being good
enough for Shakespeare, does this mean that you use the term bowels
to mean "children", as he did? Even though no one will understand what you really mean, because the standard meaning
of bowels today is "the bodily system that excretes solid
waste", or, more broadly, "the innards"? Clarity of
meaning is something we consider very important in the usage of
language. A word having a history of meaning X doesn't mean it can
be properly used to mean X today when the meaning has shifted to Y (and,
so, a word's prior meaning shouldn't influence how we use the word today
if it now has a different meaning).
The word bead originally meant "prayer" but came to be
associated with the stones of a rosary and, then, to any rounded stones
worn as jewelry. Would you say, to a stranger, "I'm going to
say a bead for my dear departed relative" just because bead
originally meant "prayer"? We think that the "if it's
good enough for Shakespeare it's good enough for me" logic is
flawed. Clear communication is paramount; sloppy communication
impedes clarity.

From Brian Degnan:

Great site, guys, as always, and glad to see
you're back better than ever in weekly working order. My question is from your last publication
in issue 113 wherein you discussed improper etymologies. One of the phrases was
wet your whistle. My question is, isn't the phrase whet your
whistle? Such as is with to whet one's appetite, I feel whet your
whistle means to stimulate your whistle; *eh-hem* that is, your
voice or throat. I don't believe that I've seen it spelled wet, unless we were using
chat room
spelling. Just my thoughts. What do you opine, fine etymologists?

So, we have wet all the way
back in Middle English and whet not heard of until the 17th
century. It's our guess that whet your whistle was simply a
misunderstanding of wet..., with influence from whet one's appetite.